Heretofore, materials having antistatic properties have been used for storage vessels for semi-conductor wafers, electronic/electric parts, floor/wall coverings for a production factory of semi-conductors, etc., wherein static electrification must be avoided.
In order to impart antistatic properties to a molded article of a synthetic resin, for example, there can be normally used a method of coating a molded article with a paint containing a carbon powder, metallic powder, etc., or a method of molding a molded article using a synthetic resin kneaded with a carbon powder, carbon fiber, metallic fiber, etc.
However, the above methods have a problem that a transparent molded article can not be obtained due to the paint and coloring of the molded article itself, and the content can not be seen through the molded article in case of application for the window part.
In order to solve the above problems, various trials have been made. For example, Japanese Laid-Open Patent Publication No. 57-85866 discloses a transparent paint comprising a conductive fine powder of tin oxide as a main component and a binder.
The above paint can forms a coating film which is transparent and has antistatic properties, however, the resulting coating film normally has low hardness because the binder is a thermoplastic resin, thereby, a coating film having excellent marring resistance and solvent resistance can not be obtained.
Further, Japanese Laid-Open Patent Publication No. 60-60166 discloses a transparent paint comprising a conductive fine powder of tin oxide as a main component and a photo-setting resin binder.
The coating film formed by using this paint is superior in marring resistance and solvent resistance, however, storage stability of the paint is liable to be affected by a temperature, humidity, etc., which results in deterioration of transparency with time. Further, the paint has a problem about process, that is, sag is arisen during coating by a normal bar coating method, doctor blade coating method, roll coating method and dipping method because of it's low viscosity. There is also a problem that productivity such as raw material efficiency is inferior and nonuniformity is arisen on the surface of the coating film during coating by a spraying method suitable for a low viscosity paint.
In order to solve such a problem about storage, Japanese Laid-Open Patent Publication No. 62-161870 discloses a technique comprising formulating a metallic chloride into a paint comprising a conductive fine powder of a tin oxide as a main component and a binder resin to improve storage stability.
However, the above paint has a problem that the production environment is contaminated with metallic ion, halogen ion or hydrochloric acid produced by hydrolysis of metallic chloride because the metallic chloride is present in the coating film.
Under these circumstances, in order to solve the above problems, the present inventors have intensively studied. As a result, the present invention has been accomplished.
The main object of the present invention is to provide a photo-setting conductive coating composition which can be easily coated by a normal coating method, and can be easily set by ultraviolet or visible radiation. to form a coating film superior in antistatic properties, transparency, hardness and marring resistance.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description.